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What octane rating of fuel do you use in your 5.7 Hemi?

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Discussion Starter #1
I did a quick search and didn't really find a discussion on this question:

I'm curious as to how many people actually use the recommended octane rated fuel for the Hemi.
 

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I always used 87 in my 09 Hemi for the first few years. Then one day I was on E stopped to get gas and they were out of 87. I put 89 in and noticed MPG was about 2MPG better. I thought it was a fluke but went ahead and did it again for the next few fill-ups. Then I did a cost per gallon vs MPG comparison and found I was getting more for my money too. Since then I've stuck with 89.
 

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yea I only put High test. If the gas station has 93, I will put that in. Lowest I go is 91. I don't use the truck everyday so I feel the higher the Octane the better off I am. Plus the difference in a gallon from 89-91 or 89-93 really isn't huge.
 

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I put 91 because each Thursday 91 and 89 are at the same price . Here most people use 87 or 91, so I don't wanna put some old 89 .
 

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...and I want to know other people's experiences so I can make an informed choice when the time comes.

Does that answer your "why"? :D
Laughed out loud at that one.

Srsly, Circuitjc, how informed is that, really. The manufacturer makes a recommendation. Out of some 300,000 buyers this year, 10 people in a forum give you a mix of responses either following or not following the recommendation. How is that informed? It's more like, "Well, Mikey did this so it must be okay..." It's certainly NOT going to help you in a warranty situation with engine problems if you didn't follow Ram's fuel guidelines. But then, you probably wouldn't bring it up, eh?
 

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Laughed out loud at that one.

Srsly, Circuitjc, how informed is that, really. The manufacturer makes a recommendation. Out of some 300,000 buyers this year, 10 people in a forum give you a mix of responses either following or not following the recommendation. How is that informed? It's more like, "Well, Mikey did this so it must be okay..." It's certainly NOT going to help you in a warranty situation with engine problems if you didn't follow Ram's fuel guidelines. But then, you probably wouldn't bring it up, eh?


its only money
 

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89
This is recommended by the people that designed an built the darn thing. It should be obvious that this will be optimal grade of fuel to use with the factory tune. One can get away with using 87 because the computer will retard the timing to prevent detonation, but there will be a small sacrifice in efficiency. Perhaps a bit less power and/or fuel economy just as texas_rebel discovered. However, no engine damage will occur and I doubt it could be grounds to void the warranty, as 87 is deemed "acceptable". Many other engines have lower compression ratios and are tuned for 87 - the 5.7 hemi is not one of them.
Since the computer is programmed to allow for 89 octane, there will generally be no benefit in using a higher grade of fuel either. Maybe a different story if you are using an aftermarket tuner or the vehicle has infrequent use though.
 

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Discussion Starter #11
...Since the computer is programmed to allow for 89 octane, there will generally be no benefit in using a higher grade of fuel either. Maybe a different story if you are using an aftermarket tuner or the vehicle has infrequent use though.
I had a programmer for my 2004 F-150 with 4.6. It needed it bad. The 4.6 was a crappy engine to tow with. One time towing my snowmobile trailer into the wind coming home from a trip up north I couldn't get over 80 km/h on the highway. My 5.0 towed awesome comparatively and I expect the Hemi to be that much better.

Srsly, Circuitjc, how informed is that, really.
Cripes guys. I was only curious. If you don't want to share then don't. No one says you have to read every post. :p
 

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Honestly, I'm just saying that a handful of guys trying to outguess the Hemi engineering team about the best fuel do not make the best experts. In other words, you may become "informed," but not "well-informed."
 

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I've used 87, just because that what I've always used in every vehicle other than my antique that needs 91... But I guess I'll be converting to mid-grade 89.
 

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I use 89 only because I want the best for truck, the same way I want the best for my 2 boys. BUT, it hurts my soul when the 87 is about 20 cents cheaper than the 89. I just have to close my eyes and pump, and make sure the wife doesn't know the truth!
 

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Around here, there is plenty of 89 octane, running around $2.25/gal. So it costs about 12 cents per mile. (averaging 18.4 right now)

91 octane is 23 cents higher per gallon. I'd have to get 2 extra mpg consistently to equal the difference in price of the gas. I haven't heard of anyone getting 20+ mpg avg with any octane on the Hemi so 89 works for me. And I don't race the truck around, so extra performance isn't an issue.
 

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91+ and Amsoil every 3k miles. Got me 225k out of my last truck and it is still going with a new owner. My gas mileage was always slightly better and with all the mods it seemed more responsive. True duals, cai, headers ...
 
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